Two Gram-positive or -variable, endospore-forming, slightly halophilic strains (SW-72T and SW-93) were isolated from sea water of the East Sea and the Yellow Sea in Korea, respectively, and subjected to polyphasic taxonomic study. Both strains had cell-wall peptidoglycan that was based on meso-diaminopimelic acid and MK-7 as the predominant menaquinone. The two strains contained large amounts of saturated and branched fatty acids, with anteiso-C15:0 as the major fatty acid. The DNA G + C contents of strains SW-72T and SW-93 were 40.9 and 41.0 mol%, respectively. Phylogenetic analysis based on 16S rDNA sequences showed that strains SW-72T and SW-93 fall within the radiation of the cluster that comprises members of the genus Bacillus, particularly Bacillus rRNA group 6. There were five nucleotide differences between the 16S rDNA sequences of strains SW-72T and SW-93. The mean level of DNA-DNA relatedness between strains SW-72T and SW-93 was 21.5%. Strains SW-72T and SW-93 showed 93.1-95.2% 16S rDNA sequence similarity to the type strains of Bacillus species that are assigned to rRNA group 6. Strains SW-72T and SW-93 could not be differentiated clearly by using their phenotypic properties. On the basis of phenotypic properties, phylogeny and genomic data, it is proposed that strain SW-72T (- KCCM 4164T=JCM 11807T) should be placed in the genus Bacillus as the type strain of a novel species, Bacillus hwajinpoensis sp. nov., and that strain SW-93 (= KCCM 41640 = JCM 11806) should be placed in the genus Bacillus as an unnamed Bacillus genomospecies.